Electronically controlled fuel injection system

ABSTRACT

An electronically controlled fuel injection system which is so designed as to adapt itself to operation of high engine speed by effecting a switching from two-cylinder simultaneous injection to four-cylinder simultaneous injection. When the engine is operating at speeds below a predetermined value, a fuel injection pulse signal, which occurs at the rate of two pulses for each rotation of the engine shaft, is applied alternately to the injection valve associated with the first and third cylinders and the injection valve associated with the second and fourth cylinders, so that fuel injection takes place simultaneously in the first and third cylinders and it is followed by a simultaneous fuel injection in the second and fourth cylinders. On the other hand, when engine speed increases to the predetermined value, a switching is effected from the twocylinder simultaneous injection to four-cylinder simultaneous injection. A switching from the four-cylinder simultaneous injection to two-cylinder simultaneous injection occurs when engine speed decreases to another predetermined value lower than said predetermined value.

United States Patent Aono et a1.

[72] Inventors: Shlgeo Aono, 3-68, Oppama-hi'gashicho; Nobuzi Manaka,3-15-1, Morisaki, both of Yokosuka, Japan [571 ABSTRACT d: Oct. 22 19:70An electronically controlled fuel injection system [22] I e which is sodesigned as to adapt itself to operation of PP 82946 high engine speedby effecting a switching from twocylinder simultaneous injection tofour-cylinder simul- [30] Foreign Appficaflon Priority Data taneousinjection. When the engine is operating at speeds below a predetemnnedvalue, a fuel in ection Oct. 22, 1969 Japan ..44/84427 pulse Signal,which occurs at the rate of two pulses f each rotation of the engineshaft, is applied alternately [52] US. Cl. ..123/32 EA, 123/119 R,123/139 E, to the injection valve associated with the first and 123/32 Rthird cylinders and the injection valve associated with [51 Int. Cl..F02b 3/00 the second and fourth cylinders, so that fuel injection [58]Field 01 Search ..123/32 EA takes place Simultaneously in the first andthird cylin ders and it is followed by a simultaneous fuel injection[56] References in the second and fourth cylinders. On the other hand,UNITED STATES PATENTS when engine s eed increases to the predeterminedvalue, a switching is effected from the two-cylinder 3,430,616 3/ 1969Glockler ..l23/32 simultaneous injection to f ylinde Simultaneous3,463,130 8/1969 Retchardt ..l23/32 injection A Switching from the f lid Simuh 3,522,794 8/1970 Relchardt ..l23/32 taneous injection to twocy|inder Simultaneous injeo 3,566,846 3/1971 Glockler ..l23/32 tionoccurs when engine Speed decreases to another 3,587,536 6/1971 lnoue..123/32 predetermined value lower than Said predetermined value.

6 Claims, Drawing Figures INTAKE MANIFOLD ENGINE PRESSURE TEMPERATURESIGNAL SIGNAL i 9 2'2 i F 27 32 43 44 i '6 1 H WAVE- RMZA COMPUTING/JINJECTlON |---1F K 3? cIRcuIT VALVE I I 20 3O II {I4 ,5 4O 34 2 J 37 KW) 33 45 46 42 we INJECTION VALVE 47 5 318 I B A I i SWITCHING r-l; S ACIRCUIT 5; 48 2 49 50 2s 35 "s ELECTRONICALLY CONTROLLED FUEL INJECTIONSYSTEM Oct. 24, 1972 Primary Examiner-Laurence M. Goodridge AssistantExaminer-Ronald B. Cox Attorney-McCarthy, Depaoli, OBrien & PricePATENTEDUBT24 I972 3.699832 sum 3 BF 3 INVENTORS SH IGEO AONO BY NO BUZI MANAKA ELECTRONICALLY CONTROLLED FUEL INJECTION SYSTEM Thisinvention relates to a fuel injection system for a multi-cylinderinternal combustion engine and more particularly to an electronicallycontrolled fuel injection system in which a switching from two-cylindersimultaneous injection to four-cylinder simultaneous injection iseffected when engine speed increases to a predetermined value.

in the ordinary electronically controlled fuel injection system, a timedfuel injection method is employed. For a four-cylinder engine intakemethod is to effect a simultaneous fuel injection in two earlier-ignitedcylinders which is followed by a simultaneous fuel injection in theremaining two later-ignited cylinders, rather than to effect a fuelinjection in each one of the four cylinders on its suction stroke. Thefuel injection takes place while an injection valve is kept actuatedthrough application thereto of a fuel injection pulse which is generatedat the rate of one for each rotation of the engine by a computingcircuit which functions to calculate a proper pulse width responsivelyto engine operating conditions, such as, engine speed, intr(e manifoldpressure and engine temperature. When the engine speed rises to, forexample, 6000 rpm it takes ms for one complete rotation of the crankshaft, the computing circuit is required to generate such a narrow pulseas having its width shorter than 5 ms. However, further increase inengine speed tends to incapacitate the computing circuit from generatingsuch pulse because of its limiting capability in computing operation,thus rendering the fuel injection system incapable of functioningproperly.

It is therefore an object of this invention to provide a new andimproved fuel injection control system for a multi-cylinder internalcombustion engine with a view to overcoming the above-stateddisadvantages.

It is another object of this invention to provide a fuel injectioncontrol system which functions to effect a switching from two-cylindersimultaneous injection to four-cylinder simultaneous injection whenengine speed increases to a predetermined value. 7

It is a further object of this invention to provide a fuel injectioncontrol system having a computing circuit adapted to function properlyeven when the engine speed increases to a relatively high value.

in the drawings:

FIG. 1 is a schematic diagram of a fuel injection control systemaccording to one embodiment of this invention;

FIG. 2 is a circuit diagram of a switching unit of the fuel injectionsystem shown in FIG. 1;

FlGS. 3(a) through (e) show pulse waveforms appearing at various pointsof the system of FIG. 1 when a two-cylinder simultaneous fuel injectionmethod is being employed;

FIGS. 4(a) through (e) are views similar to FIGS. 3(a) through (e), butshowing pulse waveforms appearing when a four-cylinder simultaneousinjection method is being employed; and

FIG. 5 shows a relationship between fuel injection methods employed andengine speed.

Referring now to-FlG. l, numeral 10 designates an engine driventriggering device incorporated in a distributor housing (not shown). Theengine driven triggering device 10 comprises a cam 11 mounted on anengine driven shaft 12 and two triggering switches 13 and 14 adapted tobe alternately actuated by rotation of the cam 11 as a function ofengine speed. Each triggering switch l3, 14 has respectively a movablecontact connected to ground and a stationary contact connected to apower supply, such as, a battery 15 via resistors l6 and 17,respectively. The stationary contacts of the triggering switches 13 and14 are also connected to a waveshaping circuit 18 by means of leads l9and 20, respectively. The waveshaping circuit 18 has two outputterminals 21 and 22 corresponding to the leads l9 and 20, respectively.One such a waveshaping circuit and its configuration is shown in FIG. 4of U. S. Pat. No. 3,430,616 to Glockler et al which may be readilyapplicable to the present invention. One of output terminal 21 isconnected by means of a lead 23 to one of the input terminals of an ORgate 24. The other output terminal 22 of the waveshaping circuit 18 isconnected by means of a lead 25 to one of the fixed contacts A of arelay switch 26. The relay switch 26 has another fixed contact B and amovable contact C which is connected to the other input terminal of theOR gate 24. The output terminal of the OR gate 24 is connected to theinput of an computing circuit 27 so that a pulse signal indicatingengine speed is supplied to the computing circuit 27. Also applied tothe computing circuit 27 are two signals representing intake manifoldpressure and engine temperature, designated at 28 and 29, respectively.In dependence on these signals representing engine operating conditions,the computing circuit 27 calculates a proper pulse width and generates atrain of pulses having the proper pulse width. The pulses thus generatedare supplied to two terminals of the AND gates 30 and 31 at their oneinputs by way of leads 32 and 33, respectively. One such a computingcircuit and its configuration is shown in FIG. 5 of U. S. Pat. No.3,430,616 which may be readily applicable to the present invention.

The lead 25 form one output terminal 22 of the waveshaping circuit 18 isconnected by means of a lead 34 to one of the fixed contacts A ofanother relay switch 35, the movable contact C of which is connected bymeans of a lead 36 to the other input terminal of the AND gate 30.Likewise, the lead 23 from the other output terminal 21 of thewaveshaping circuit 18 is connected by means of a lead 37 to one of thefixed contacts A" of still another relay switch 38 whose movable contactC" is connected by means of a lead 39 to the other input terminal of theAND gate 30. The leads 34 and 37 are also connected by means of leads 40and 41 to the two input terminals of another OR gate 42, the outputterminal of which is connected to each fixed terminal B and B" of thetwo relay switches 35 and 38.

The AND gate 30 has its output terminal connected to an amplifier 43which in turn is connected to an injection valve 44 associated with thefirst and third cylinders. Likewise, the AND gate 31 has its outputterminal leading to another amplifier 45 which in turn is connected toan injection valve 46 associated with the second and fourth cylinders.The leads 23 and 25 from the output terminals 21 and 22 of thewaveshaping circuit 18 are also connected by means of leads 47 and 48 toa switching circuit 49, the construction and operation of which will befully described later with nected to a relay coil 50 which, uponenergization,

moves the movable contacts C, C and C" of the relay switches 26, 35 and38 from contact with their fixed contacts A, A" and A" into engagementwith B, B and FIG. 2 shows a circuit diagram of the switching circuit 49which functions to effect a change-over in injection method between twoand four-cylinder simultaneous injection. The input terminals 51 and 52of the switching circuit 49 are connected to the leads 47 and 48,respectively, so i that rectangular pulse signals representing enginespeed are supplied from the waveshaping circuit 18 to the switchingcircuit 49. Connected to the input terminals 51 and 52 are two seriesconnections of capacitors 53 and 54, diodes 55 and 56 and resistors 57and 58, respectively, the resistors 57 and 58 being connected togetherto a capacitor 59 having one end grounded. These two series connectionsand the capacitor 59 act as a means for converting the pulse signal intodc voltage proportional to engine speed. The dc voltage is applied tothe base of transistor 60 which forms a major part of a voltagecomparing unit or a Schmitt circuit, generally indicated at 61. The baseof the transistor 60 is grounded via a resistor 62 and is also connectedvia a resistor 63 to a bus line 64 connected to a battery. Thetransistor 60 has its emitter grounded via a resistor 65 and itscollector connected to the bus line 64 via a resistor 66. The collectoris also connected to the base of another transistor 67 by way of aresistor 68. The emitter of the transistor 60 is also connected to theemitter of the transistor 67 by way of a resistor 681. The transistor 67has its collector connected to a terminal 101 and the bus line 64 via aresistor 69 and its baseconnected to ground via a resistor 70. Theresistance valueof the resistors 62, 63 and 65 are adjusted so that whenthe-engine speed increases to a predetermined value the potential at thebase of the transistor 60 is high enough to turn it on. Upon thetransistor 60 conducting, the potential at the collector thereofdecreases so much that the transistor 67 is rendered nonconductive. Whenthis occurs, the potential at the collector of the transistor 67 buildsup.

Shown in the upper right-hand portion of FIG. 2 is a relay unit 71adapted for use with the Schmitt circuit 61 by connecting the terminal101 with a terminal 102 to actuate the three relay switches 26, 35 and38 when the engine speed rises to the predetermined value. The relayunit 71 comprises a transistor 72 having its base connected via aresistor 73 to the terminal 102 and a relay coil 74 connected in seriesto the transistor 72. The emitter of the transistor 72 is connecteddirectly to ground and the relay coil 74 is connected to a battery.Thus, when the engine speed rises to the predetermined value, thetransistor 60 isrendered into conduction, causing the transistor 67 tobe rendered nonconductive, which in turn renders the transistor 72conductive. As a result, the relay coil 74 is energized to move themovable contacts C, C and C" of the three relay switches 26, 35 and 38into engagement with the respective fixed contacts B, B and B".

A transistor circuit 75 including circuits 26', 35' and 38' may take theplace of the relay unit 71 by disconnecting the terminal 101 from "theterminal 102 and connecting the terminal 101 with a terminal 103. The

circuits 26, 35' and 38' are the same circuit and correspond to therelay switch 26, 35 and 38, respectively. Specially expressing thecircuit 26', the terminal 103 is connected via a resistor 76 to the baseof a transistor 77, the emitter thereof being grounded. The transistor77 has its collector connected to a battery via a resistor 78 and alsoto the base of another transistor 79 via a resistor 80. The collector ofthe transistor 79 is connected through a resistor 81 to a terminal A,which corresponds to the fixed contact A of the relay switch 26. Thetransistor 79 has its emitter connected to a terminal C, whichcorresponds to the movable contact C of the relay switch 26. Connectedto the terminal C, is the emitter of a transistor 82 whose base isconnected to the collector of the transistor 67 via a resistor 83. Thetransistor 82 has its collector connected through a resistor 84 to aterminal B, which corresponds to the fixed contact B of the relay switch26.

Operation of this transistor circuit is such that when the engine isoperating at speeds below the predetermined value the transistor 67 isheld conductive and therefore the transistor 77 is nonconducting. Thus,a high voltage at the collector of the transistor 77 is applied to thebase of a transistor 79 to render it conductive, so that a current pathis established between the terminals A and C, by way of the transistor79. On the other hand, when the engine speed increases to a certainpredetermined value, the transistor 67 is rendered nonconductive causingthe potential at the collector thereof to build up. Thus, the transistor77 is turned on and render the transistor 79 nonconductive so as tocutoff the current path between the terminals A and C,, while thetransistor 82 is rendered conductive to establish a current path betweenthe terminals B, and C by way of the transistor 82.

In the operation of the control system shown in FIG. 1, when the engineis operating, the cam 11 mounted on the engine driven shaft 12 opens andcloses the two triggering switches 13 and 14 alternately in dependenceon the rotation of the engine driven shaft to generate alternate pulsesignals to the leads 19 and 20. The pulse signal is supplied to thewaveshaping circuit 18 where it is shaped into rectangular wave as shownin FIGS. 3(a) and (b), in which (a) represents a rectangular wave-formappearing at the output terminal 21 and (b) at the output terminal 22.As described above, when the engine is operating at speeds below apredetermined value, each of the movable contacts C of the relayswitches 26, 35 and 38 are kept in electrical contact with theirassociated fixed contact A, A and A", so that the rectangular wavesignals on both of the leads 23 and 25 are applied to the respectiveinput terminals of the OR gate 24. Each time the two triggering switches13 and 14 are made to open and close their contacts by rotation of thecam 11, one rectangular pulse is applied to the computing circuit 27.The computing circuit 27 functions to calculate a proper pulse width onthe basis of engine speed, intake manifold pressure and enginetemperature to generate a train of pulses having such width, the pulsesbeing shown in FIG. 3(0). The train of pulses are applied to the ANDgates 30 and 31 at their one inputs by means of the leads 32 and 33. Therectangular wave signal at the output terminal 22 of the waveshapingcircuit 18 is also fed to the relay switch 35 by means of the leads25and 34 and thence to the other input of the AND gate 30 by means ofthe lead 36. Likewise, the rectangular wave signal at the other outputterminal 21 of the waveshap ing circuit 18 is also fed to the relayswitch 38 by means of the leads 23 and 37 and thence to the other inputof the AND gate 31 by means of the lead 39.

When the pulse signals applied to the two input terminals of the ANDgate 30 are in phase with each other, that is, coincidewith each other,the AND gate 30 produces an output pulse during the overlap of thesesignals, as shown in FIG. 3(d). Likewise, the output pulse of the ANDgate 31 occurs during the overlap of the pulse signals applied thereto,as shown in FIG. 3(e). These output pulses are transmitted to therespective amplifiers 43 and 45 and are then applied to the respectiveinjection valves 44 and 46. The injection valve 44, which is mounted inthe first and third injection nozzles (not shown), is kept open whilethe output pulse is applied to the injection valve 44, and the injectionvalve 46 mounted in the second and fourth cylinders (not shown) is keptopen while the output pulse is applied to the injection valve 46. Since,as shown in FIGS. 3(d) and (e), the output pulse is generatedalternately by the AND gates 30 and 31 at the rate of two for eachrotation of the engine, fuel injection occurssimultaneously in the firstand third cylinders and it is followed by the simultaneous fuelinjection in the second and fourth cylinders.

On the other hand, when the engine speed increases above thepredetermined value, the switching circuit 49 operates to energize therelay unit 71 so that the movable contacts C, C and C" of the relayswitches 26, 35 and 38 are moved from contact with the respective fixedcontacts A, A and A" into contact with the respective fixed contacts B,B' and B". In the case of the transistor circuit 75 shown in FIG. 2, acurrent path is established between the terminals B, and C, while thecurrent path between the terminals A, and C, is cutoff. Since the relayswitch 26 disconnects the one input of the OR gate 24 from the leadconnected to one of the outputs of the waveshaping circuit 18, thecomputing circuit 27 is actuated only by the output pulse suppliedthrough the lead 23. Therefore, the computing circuit 27 generates apulse signal which occurs at the rate of one pulse per each rotation ofthe engine, as shown in FIG. 4(c). This pulse signal is applied to theAND gates and 31 at their one inputs.

The rectangular wave signals on the leads 23 and 25 are transmitted tothe input terminals of the OR gate 42 by way of the leads 41 and 40,respectively. Since, as shown in FIG. 4(a) and (b), the output pulsealways exists on either the lead 23 or 25, the OR gate 42 is kept *ON"at all times, so that the output signal is always applied to the ANDgates 30 and 31 at the other outputs thereof. Thus, the AND gates 30 and31 produce output pulses simultaneously AND they receive input signalsfrom the computing circuit 27, as shown in FIGS. 4(d) and (e). Theoutput pulses are supplied to the amplifiers 43 and 45 for amplificationand thence to the injection valves 44 and 46, so that fuel injectionoccurs in the four cylinders simultaneously.

It has been found that from the viewpoint of engine operation it ispreferable to effect a changeover from four-cylinder simultaneousinjection to two-cylinder simultaneous injection at a point of enginespeed lower than that at which the switching from two to fourcylindersimultaneous injection is effected, as shown in FIG. 5. This hysteresischaracteristic of the relationship between the fuel injection methodsemployed and engine speed can be obtained by adjusting the resistancevalue of the resistors and 681 of the Schmitt circuit 61 shown in FIG.2.

Although description of this invention has been made in connection withthe fuel injection system in which a switching between two andfour-cylinder fuel injection is effected this invention is applicablealso to the following cases:

one-cylinder injection twocylinder simultaneous four-cylinder inventionengine two-cylinder fourcylinder simultaneous injection threecylindersimultaneous injection simultaneous injection one-cylinder injectionsimultaneous injection one-cylinder injection either-cylindertwo-cylinder engine simultaneous injection four-cylinder simultaneousinjection What is claimed is:

I. An electronically controlled fuel injection system fora-multi-cylinder internal combustion engine, comprising: frrst means forproducing at least one pulse signal having a repetition frequencyproportional to the speed of the internal combustion engine; secondmeans for producing a control signal during a time interval from amoment when said repetition frequency of the pulse signal exceeds afirst predetermined value to another moment when said repetitionfrequency lowers below a second predetermined value smaller than saidfirst predetermined value; third means simultaneously producing at leasttwo drive signals each having a pulse width proportional to saidrepetition frequency of the pulse signal, the intake manifold pressureand the engine temperature when said third means receivessaid controlsignal; and at least two injection valves each adapted to receive one ofsaid drive signal and associated with a nozzle positioned within one ofthe cylinders, each of said. valves being adapted to supply switchesadapted to be actuated by the cam in dependence upon the motion of theengine-driven shaft, and a waveshaping circuit having two inputterminals connected to said triggering switches and having two outputterminals.

3; An electronically controlled fuel injection system according to claim1, wherein said third means comprises a first OR gate having two inputterminals, one of said input terminals being connected directly to oneof the two output terminals of said waveshaping circuit, a firstswitching element for connecting and disconnecting the other inputterminal of said first OR gate to and from the other output terminal ofsaid wave-shaping circuit, a computing circuit having its input terminalconnected to the output terminal of said first OR gate, two AND gateseach having two input terminals, one of said two input terminals of eachsaid AND gate being connected to the output of said computing circuit, asecond OR gate having two input terminals each connected to a respectiveoutput terminal of said waveshaping circuit, and second and thirdswitching elements each for selectively connecting the other inputterminals of the respectively associated AND gates to the outputterminals of said waveshaping circuit and to the output terminal of saidsecond OR gate.

4. An electronically controlled fuel injection system according to claim1, wherein said second means includes an OR gate having two inputsconnected to said two output terminals of the waveshaping circuit and anoutput, a Schmitt circuit having an input connnected to said output ofthe OR gate and an output, and an amplifier having an input connected tosaid output of the Schmitt circuit and an output connected to saidswitching elements.

5. An electronically controlled fuel injection system according to claim3, wherein said first, second and third switching elements are relayswitches.

6. An electronically controlled fuel injection system according to claim3, wherein said first, second and third switching elements are switchingcircuits including transistors.

1. An electronically controlled fuel injection system for amulti-cylinder internal combustion engine, comprising: first means forproducing at least one pulse signal having a repetition frequencyproportional to the speed of the internal combustion engine; secondmeans for producing a control signal during a time interval from amoment when said repetition frequency of the pulse signal exceeds afirst predetermined value to another moment when said repetitionfrequency lowers below a second predetermined value smaller than saidfirst predetermined value; third means simultaneously producing at leasttwo drive signals each having a pulse width proportional to saidrepetition frequency of the pulse signal, the intake manifold pressureand the engine temperature when said third means receives said controlsignal; and at least two injection valves each adapted to receive one ofsaid drive signal and associated with a nozzle positioned within one ofthe cylinders, each of said valves being adapted to supply fuel to saidnozzle.
 2. An electronically controlled fuel injection system accordingto claim 1, wherein said first means includes an engine-driventriggering device having a cam mounted on an engine-driven shaft and twotriggering switches adapted to be actuated by the cam in dependence uponthe motion of the engine-driven shaft, and a waveshaping circuit havingtwo input terminals connected to said triggering switches and having twooutput terminals.
 3. An electronically controlled fuel injection systemaccording to claim 1, wherein said third means comprises a first OR gatehaving two input terminals, one of said input terminals being connecteddirectly to one of the two output terminals of said waveshaping circuit,a first switching element for connecting and disconnecting the otherinput terminal of said first OR gate to and from the other outputterminal of said wave-shaping circuit, a computing circuit having itsinput terminal connected to the output terminal of said first OR gate,two AND gates each having two input terminals, one of said two inputterminals of each said AND gate being connected to the output of saidcomputing circuit, a second OR gate having two input terminals eachconnected to a respective output terminal of said waveshaping circuit,and second and third switching elements each for selectively connectingthe other input terminals of the respectively associated AND gates tothe output terminals of said waveshaping circuit and to the outputterminal of said second OR gate.
 4. An electronically controlled fuelinjection system according to claim 1, wherein said second meansincludes an OR gate having two inputs connected to said two outputterminals of the waveshaping circuit and an output, a Schmitt circuithaving an input connnected to said output of the OR gate and an output,and an amplifier having an input connected to said output of the Schmittcircuit and an output connected to said switching elements.
 5. Anelectronically controlled fuel injection system according to claim 3,wherein said first, second and third switching elements are relayswitches.
 6. AN electronically controlled fuel injection systemaccording to claim 3, wherein said first, second and third switchingelements are switching circuits including transistors.